Fix timestamp handling

SessionMessagingKit/Sending & Receiving/MessageReceiver.swift

@@ -85,6 +85,7 @@ internal enum MessageReceiver {
         if let message = message {
             message.sender = sender
             message.recipient = Configuration.shared.storage.getUserPublicKey()
+            message.sentTimestamp = envelope.timestamp
             message.receivedTimestamp = NSDate.millisecondTimestamp()
             message.groupPublicKey = groupPublicKey
             message.openGroupServerMessageID = messageServerID

SignalUtilitiesKit/Messaging/TSIncomingMessage+Conversion.swift

@@ -4,7 +4,7 @@ public extension TSIncomingMessage {
     static func from(_ visibleMessage: VisibleMessage, associatedWith thread: TSThread, using transaction: YapDatabaseReadWriteTransaction) -> TSIncomingMessage {
         let sender = visibleMessage.sender!
         let result = TSIncomingMessage(
-            timestamp: visibleMessage.receivedTimestamp!,
+            timestamp: visibleMessage.sentTimestamp!,
             in: thread,
             authorId: sender,
             sourceDeviceId: 1,